Pur-alpha regulates cytoplasmic stress granule dynamics and ameliorates FUS toxicity

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Amyotrophic lateral sclerosis (ALS) involves motor neuron loss, with mutations in RNA-binding proteins like FUS linked to pathology.
• Pur-alpha, a DNA/RNA-binding protein, interacts with C9orf72 repeat expansions and may influence ALS pathogenesis.
• The precise role of Pur-alpha in ALS progression remains unclear.

Purpose of the Study:

• To investigate the function of Pur-alpha in Amyotrophic Lateral Sclerosis (ALS) pathogenesis.
• To determine Pur-alpha's role in the formation and dynamics of cytoplasmic stress granules (SGs) in ALS.
• To assess Pur-alpha's potential as a therapeutic target for ALS.

Main Methods:

• Identification of Pur-alpha in cytoplasmic stress granules within ALS patient cells harboring FUS mutations.
• Co-localization studies of Pur-alpha with mutant FUS under cellular stress.
• Assessment of Pur-alpha's interaction with FUS in mammalian neuronal cells.
• RNA interference (shRNA) to knock down endogenous Pur-alpha and observe effects on SG formation.
• Ectopic expression of Pur-alpha to evaluate its impact on mutant FUS mislocalization and toxicity in primary motor neurons.

Main Results:

• Pur-alpha was identified as a novel component of cytoplasmic stress granules in ALS patient cells with FUS mutations.
• Pur-alpha co-localized with mutant FUS and became trapped in stress granules upon cellular stress.
• Pur-alpha physically interacted with FUS in mammalian neuronal cells.
• Knockdown of Pur-alpha reduced cytoplasmic stress granule formation, indicating its essential role.
• Overexpression of Pur-alpha prevented mutant FUS mislocalization and reduced its toxicity in motor neurons.

Conclusions:

• Pur-alpha is a crucial regulator of cytoplasmic stress granule dynamics in the context of ALS.
• The findings highlight the significance of stress granules in ALS pathogenesis.
• Pur-alpha emerges as a potential therapeutic target for mitigating mutant FUS toxicity in ALS.